Network Rail engineers are working to repair the damage. But only four out of the six lines running into London Paddington are now operational.

A number of services running between Reading and London Paddington have been cancelled and there are no Heathrow Connect services running to or from the London station.

In a statement GWR said: "At the moment, we expect to be able to run around half our normal service into and out of Paddington on Friday, June 17.

"We hope this will improve as further progress is made and we would ask customers to check before travel and only travel if absolutely necessary."

"We apologise"

"We recognise the severe inconvenience caused to many of our customers and for this we apologise."

GWR is also advising customers on South West Trains services between Reading and London Waterloo to travel via Guildford or Basingstoke as services are expected to be crammed with people heading to Royal Ascot.

If you have been affected by delays or cancellations you can see if you're eligible for compensation here .